111
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1 /* Structured Exception Handling (SEH) runtime interface routines.
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145
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2 Copyright (C) 2010-2020 Free Software Foundation, Inc.
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111
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3
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4 This file is part of GCC.
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5
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6 GCC is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 3, or (at your option)
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9 any later version.
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10
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11 GCC is distributed in the hope that it will be useful, but WITHOUT
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12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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14 License for more details.
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15
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16 Under Section 7 of GPL version 3, you are granted additional
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17 permissions described in the GCC Runtime Library Exception, version
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18 3.1, as published by the Free Software Foundation.
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19
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20 You should have received a copy of the GNU General Public License and
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21 a copy of the GCC Runtime Library Exception along with this program;
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22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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23 <http://www.gnu.org/licenses/>. */
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24
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25 #include "tconfig.h"
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26 #include "tsystem.h"
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27 #include "coretypes.h"
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28 #include "tm.h"
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29 #include "unwind.h"
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30
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31 #if defined (__SEH__) && !defined (__USING_SJLJ_EXCEPTIONS__)
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32
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33 /* At the moment everything is written for x64, but in theory this could
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34 also be used for i386, arm, mips and other extant embedded Windows. */
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35 #ifndef __x86_64__
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36 #error "Unsupported architecture."
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37 #endif
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38
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39 /* Define GCC's exception codes. See
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40 http://msdn.microsoft.com/en-us/library/het71c37(v=VS.80).aspx
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41 In particular, MS defines bits:
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42 [31:30] = 3 (error), 2 (warning), 1 (info), 0 (success)
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43 [29] = 1 (user-defined)
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44 [28] = 0 (reserved)
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45 We define bits:
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46 [24:27] = type
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47 [0:23] = magic
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48 We set "magic" to "GCC", which is similar to MVC++ which uses "msc"
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49 as the low 3 bytes of its user-defined codes for C++ exceptions.
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50
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51 We define the ExceptionInformation entries as follows:
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52 [0] = _Unwind_Exception pointer
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53 [1] = target frame
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54 [2] = target ip
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55 [3] = target rdx
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56 */
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57
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58 #define STATUS_USER_DEFINED (1U << 29)
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59
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60 #define GCC_MAGIC (('G' << 16) | ('C' << 8) | 'C')
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61 #define GCC_EXCEPTION(TYPE) \
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62 (STATUS_USER_DEFINED | ((TYPE) << 24) | GCC_MAGIC)
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63
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64 #define STATUS_GCC_THROW GCC_EXCEPTION (0)
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65 #define STATUS_GCC_UNWIND GCC_EXCEPTION (1)
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66 #define STATUS_GCC_FORCED GCC_EXCEPTION (2)
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67
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68
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69 struct _Unwind_Context
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70 {
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71 _Unwind_Word cfa;
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72 _Unwind_Word ra;
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73 _Unwind_Word reg[2];
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74 PDISPATCHER_CONTEXT disp;
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75 };
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76
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77 /* Get the value of register INDEX as saved in CONTEXT. */
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78
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79 _Unwind_Word
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80 _Unwind_GetGR (struct _Unwind_Context *c, int index)
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81 {
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82 if (index < 0 || index >= 2)
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83 abort ();
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84 return c->reg[index];
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85 }
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86
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87 /* Overwrite the saved value for register INDEX in CONTEXT with VAL. */
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88
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89 void
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90 _Unwind_SetGR (struct _Unwind_Context *c, int index, _Unwind_Word val)
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91 {
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92 if (index < 0 || index >= 2)
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93 abort ();
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94 c->reg[index] = val;
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95 }
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96
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97 /* Get the value of the CFA as saved in CONTEXT. */
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98
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99 _Unwind_Word
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100 _Unwind_GetCFA (struct _Unwind_Context *c)
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101 {
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102 return c->cfa;
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103 }
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104
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105 /* Retrieve the return address for CONTEXT. */
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106
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107 _Unwind_Ptr
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108 _Unwind_GetIP (struct _Unwind_Context *c)
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109 {
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110 return c->ra;
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111 }
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112
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113 /* Retrieve the return address and flag whether that IP is before
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114 or after first not yet fully executed instruction. */
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115
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116 _Unwind_Ptr
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117 _Unwind_GetIPInfo (struct _Unwind_Context *c, int *ip_before_insn)
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118 {
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119 /* ??? Is there a concept of a signal context properly? There's
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120 obviously an UNWP_PUSH_MACHFRAME opcode, but the runtime might
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121 have arranged for that not to matter, really. */
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122 *ip_before_insn = 0;
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123 return c->ra;
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124 }
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125
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126 /* Overwrite the return address for CONTEXT with VAL. */
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127
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128 void
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129 _Unwind_SetIP (struct _Unwind_Context *c, _Unwind_Ptr val)
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130 {
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131 c->ra = val;
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132 }
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133
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134 void *
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135 _Unwind_GetLanguageSpecificData (struct _Unwind_Context *c)
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136 {
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137 return c->disp->HandlerData;
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138 }
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139
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140 _Unwind_Ptr
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141 _Unwind_GetRegionStart (struct _Unwind_Context *c)
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142 {
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143 return c->disp->FunctionEntry->BeginAddress + c->disp->ImageBase;
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144 }
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145
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146 void *
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147 _Unwind_FindEnclosingFunction (void *pc)
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148 {
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149 PRUNTIME_FUNCTION entry;
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150 ULONG64 ImageBase;
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151
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152 entry = RtlLookupFunctionEntry ((ULONG64)pc, &ImageBase, NULL);
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153
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154 return (entry ? (void *)(entry->BeginAddress + ImageBase) : NULL);
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155 }
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156
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157 _Unwind_Ptr
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158 _Unwind_GetDataRelBase (struct _Unwind_Context *c ATTRIBUTE_UNUSED)
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159 {
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160 return 0;
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161 }
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162
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163 _Unwind_Ptr
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164 _Unwind_GetTextRelBase (struct _Unwind_Context *c)
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165 {
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166 return c->disp->ImageBase;
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167 }
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168
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169
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170 /* The two-phase unwind process that GCC uses is ordered differently
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171 from the two-phase unwind process that SEH uses. The mechansism
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172 that GCC uses is to have the filter return _URC_HANDER_FOUND; the
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173 mechanism that SEH uses is for the filter function call back into
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174 the unwinder.
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175
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176 An Ideal port to SEH would have GCC emit handler functions that
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177 can be called, given a pointer to the "EstablisherFrame" (i.e.
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178 the frame pointer base of the user-level function) can manipulate
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179 the user-level variables within the user-level function's stack
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180 frame. Once done manipulating the variables, it would return
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181 a ExceptionContinueSearch, and the unwind process would continue.
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182
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183 GCC has always done things a bit differently. We continue to
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184 transfer control back into the user-level function which, once
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185 done manipulating the user-level variables, re-throws the exception. */
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186
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187 /* The "real" language-specific personality handler forwards to here
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188 where we handle the MS SEH state and transforms it into the GCC
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189 unwind state as per GCC's <unwind.h>, at which point we defer to
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190 the regular language-specfic exception handler, which is passed in. */
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191
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192 EXCEPTION_DISPOSITION
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193 _GCC_specific_handler (PEXCEPTION_RECORD ms_exc, void *this_frame,
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194 PCONTEXT ms_orig_context, PDISPATCHER_CONTEXT ms_disp,
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195 _Unwind_Personality_Fn gcc_per)
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196 {
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197 DWORD ms_flags = ms_exc->ExceptionFlags;
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198 DWORD ms_code = ms_exc->ExceptionCode;
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199
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200 struct _Unwind_Exception *gcc_exc
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201 = (struct _Unwind_Exception *) ms_exc->ExceptionInformation[0];
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202 struct _Unwind_Context gcc_context;
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203 _Unwind_Action gcc_action;
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204 _Unwind_Reason_Code gcc_reason;
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205
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206 if (ms_flags & EXCEPTION_TARGET_UNWIND)
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207 {
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208 /* This frame is known to be the target frame. We've already
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209 "installed" the target_ip and RAX value via the arguments
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210 to RtlUnwindEx. All that's left is to set the RDX value
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211 and "continue" to have the context installed. */
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212 ms_disp->ContextRecord->Rdx = ms_exc->ExceptionInformation[3];
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213 return ExceptionContinueSearch;
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214 }
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215
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216 if (ms_code == STATUS_GCC_UNWIND)
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217 {
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218 /* This is a colliding exception that we threw so that we could
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219 cancel the already in-flight exception and stop in a frame
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220 that wanted to perform some unwind action. The only relevant
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221 test is that we're the target frame. */
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222 if (ms_exc->ExceptionInformation[1] == (_Unwind_Ptr) this_frame)
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223 {
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224 RtlUnwindEx (this_frame, (PVOID) ms_exc->ExceptionInformation[2],
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225 ms_exc, gcc_exc, ms_orig_context,
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226 ms_disp->HistoryTable);
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227 abort ();
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228 }
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229 return ExceptionContinueSearch;
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230 }
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231
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232 gcc_context.cfa = ms_disp->ContextRecord->Rsp;
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233 gcc_context.ra = ms_disp->ControlPc;
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234 gcc_context.reg[0] = 0xdeadbeef; /* These are write-only. */
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235 gcc_context.reg[1] = 0xdeadbeef;
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236 gcc_context.disp = ms_disp;
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237
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238 if (ms_code == STATUS_GCC_FORCED)
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239 {
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240 _Unwind_Stop_Fn stop = (_Unwind_Stop_Fn) gcc_exc->private_[0];
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241 void *stop_argument = (void *) gcc_exc->private_[4];
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242
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243 gcc_action = _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE;
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244
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245 stop (1, gcc_action, gcc_exc->exception_class, gcc_exc,
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246 &gcc_context, stop_argument);
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247
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248 goto phase2;
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249 }
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250
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251 /* ??? TODO: handling non-gcc user-defined exceptions as foreign. */
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252 if (ms_code != STATUS_GCC_THROW)
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253 return ExceptionContinueSearch;
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254
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255 if (ms_flags & (EXCEPTION_UNWINDING | EXCEPTION_EXIT_UNWIND))
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256 {
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257 /* This is Phase 2. */
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258 /* We know this isn't the target frame because we've already tested
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259 EXCEPTION_TARGET_UNWIND. The remaining possibility is that the
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260 gcc personality has unwind code to run. */
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261
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262 gcc_action = _UA_CLEANUP_PHASE;
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263 phase2:
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264 gcc_reason = gcc_per (1, gcc_action, gcc_exc->exception_class,
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265 gcc_exc, &gcc_context);
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266
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267 if (gcc_reason == _URC_CONTINUE_UNWIND)
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268 return ExceptionContinueSearch;
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269
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270 if (gcc_reason == _URC_INSTALL_CONTEXT)
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271 {
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272 /* Scratch space for the bits for the unwind catch. */
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273 ms_exc->ExceptionInformation[1] = (_Unwind_Ptr) this_frame;
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274 ms_exc->ExceptionInformation[2] = gcc_context.ra;
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275 ms_exc->ExceptionInformation[3] = gcc_context.reg[1];
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276
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277 /* Cancel the current exception by raising another. */
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278 RaiseException (STATUS_GCC_UNWIND, EXCEPTION_NONCONTINUABLE,
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279 4, ms_exc->ExceptionInformation);
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280
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281 /* Is RaiseException declared noreturn? */
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282 }
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283
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284 /* In _Unwind_RaiseException_Phase2 we return _URC_FATAL_PHASE2_ERROR. */
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285 }
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286 else
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287 {
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288 /* This is Phase 1. */
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289 gcc_reason = gcc_per (1, _UA_SEARCH_PHASE, gcc_exc->exception_class,
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290 gcc_exc, &gcc_context);
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291
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292 if (gcc_reason == _URC_CONTINUE_UNWIND)
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293 return ExceptionContinueSearch;
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294
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295 if (gcc_reason == _URC_HANDLER_FOUND)
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296 {
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297 /* We really need some of the information that GCC's personality
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298 routines compute during phase 2 right now, like the target IP.
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299 Go ahead and ask for it now, and cache it. */
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300 gcc_reason = gcc_per (1, _UA_CLEANUP_PHASE | _UA_HANDLER_FRAME,
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301 gcc_exc->exception_class, gcc_exc,
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302 &gcc_context);
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303 if (gcc_reason != _URC_INSTALL_CONTEXT)
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304 abort ();
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305
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306 gcc_exc->private_[1] = (_Unwind_Ptr) this_frame;
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307 gcc_exc->private_[2] = gcc_context.ra;
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308 gcc_exc->private_[3] = gcc_context.reg[1];
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309
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310 ms_exc->NumberParameters = 4;
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311 ms_exc->ExceptionInformation[1] = (_Unwind_Ptr) this_frame;
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312 ms_exc->ExceptionInformation[2] = gcc_context.ra;
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313 ms_exc->ExceptionInformation[3] = gcc_context.reg[1];
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314
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315 /* Begin phase 2. Perform the unwinding. */
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316 RtlUnwindEx (this_frame, (PVOID)gcc_context.ra, ms_exc,
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317 (PVOID)gcc_context.reg[0], ms_orig_context,
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318 ms_disp->HistoryTable);
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319 }
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320
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321 /* In _Unwind_RaiseException we return _URC_FATAL_PHASE1_ERROR. */
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322 }
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323 abort ();
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324 }
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325
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326 /* Raise an exception, passing along the given exception object. */
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327
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328 _Unwind_Reason_Code
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329 _Unwind_RaiseException (struct _Unwind_Exception *exc)
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330 {
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331 memset (exc->private_, 0, sizeof (exc->private_));
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332
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333 /* The ExceptionInformation array will have only 1 element, EXC. */
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334 RaiseException (STATUS_GCC_THROW, 0, 1, (ULONG_PTR *)&exc);
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335
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336 /* The exception handler installed in crt0 will continue any GCC
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337 exception that reaches there (and isn't marked non-continuable).
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338 Returning allows the C++ runtime to call std::terminate. */
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339 return _URC_END_OF_STACK;
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340 }
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341
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342 /* Resume propagation of an existing exception. This is used after
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343 e.g. executing cleanup code, and not to implement rethrowing. */
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344
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345 void
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346 _Unwind_Resume (struct _Unwind_Exception *gcc_exc)
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347 {
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348 UNWIND_HISTORY_TABLE ms_history;
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349 EXCEPTION_RECORD ms_exc;
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350 CONTEXT ms_context;
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351
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352 memset (&ms_exc, 0, sizeof(ms_exc));
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353 memset (&ms_history, 0, sizeof(ms_history));
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354
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355 /* ??? Not 100% perfect, since we aren't passing on the *original*
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356 exception context, but should be good enough. */
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357 ms_exc.ExceptionCode = STATUS_GCC_THROW;
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358 ms_exc.ExceptionFlags = EXCEPTION_NONCONTINUABLE;
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359 ms_exc.NumberParameters = 4;
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360 ms_exc.ExceptionInformation[0] = (ULONG_PTR) gcc_exc;
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361 ms_exc.ExceptionInformation[1] = gcc_exc->private_[1];
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362 ms_exc.ExceptionInformation[2] = gcc_exc->private_[2];
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363 ms_exc.ExceptionInformation[3] = gcc_exc->private_[3];
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364
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365 ms_context.ContextFlags = CONTEXT_ALL;
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366 RtlCaptureContext (&ms_context);
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367
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368 RtlUnwindEx ((void *) gcc_exc->private_[1], (PVOID)gcc_exc->private_[2],
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369 &ms_exc, gcc_exc, &ms_context, &ms_history);
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370
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371 /* Is RtlUnwindEx declared noreturn? */
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372 abort ();
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373 }
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374
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375 static _Unwind_Reason_Code
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376 _Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception *exc)
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377 {
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378 _Unwind_Stop_Fn stop;
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379 void * stop_argument;
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380
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381 RaiseException (STATUS_GCC_FORCED, 0, 1, (ULONG_PTR *)&exc);
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382
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383 /* If we get here, we got to top-of-stack. */
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384 /* ??? We no longer have a context pointer to pass in. */
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385
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386 stop = (_Unwind_Stop_Fn) exc->private_[0];
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387 stop_argument = (void *) exc->private_[4];
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388 stop (1, _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE | _UA_END_OF_STACK,
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389 exc->exception_class, exc, NULL, stop_argument);
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390
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391 return _UA_END_OF_STACK;
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392 }
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393
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394 _Unwind_Reason_Code
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395 _Unwind_Resume_or_Rethrow (struct _Unwind_Exception *exc)
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396 {
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397 if (exc->private_[0] == 0)
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398 _Unwind_RaiseException (exc);
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399 else
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400 _Unwind_ForcedUnwind_Phase2 (exc);
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401 abort ();
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402 }
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403
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404 /* Raise an exception for forced unwinding. */
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405
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406 _Unwind_Reason_Code
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407 _Unwind_ForcedUnwind (struct _Unwind_Exception *exc,
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408 _Unwind_Stop_Fn stop, void * stop_argument)
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409 {
|
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410 /* ??? This is a hack that only works with _GCC_specific_handler.
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411 There's no way to invoke STOP within frames that use a different
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412 exception handler. This is essentially just good enough to run
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413 the code within the gcc testsuite. */
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414
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415 memset (exc->private_, 0, sizeof (exc->private_));
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416 exc->private_[0] = (_Unwind_Ptr) stop;
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417 exc->private_[4] = (_Unwind_Ptr) stop_argument;
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418
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419 return _Unwind_ForcedUnwind_Phase2 (exc);
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420 }
|
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421
|
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422 /* A convenience function that calls the exception_cleanup field. */
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423
|
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424 void
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425 _Unwind_DeleteException (struct _Unwind_Exception *exc)
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426 {
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427 if (exc->exception_cleanup)
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428 (*exc->exception_cleanup) (_URC_FOREIGN_EXCEPTION_CAUGHT, exc);
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429 }
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430
|
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431 /* Perform stack backtrace through unwind data. */
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432
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433 _Unwind_Reason_Code
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434 _Unwind_Backtrace(_Unwind_Trace_Fn trace,
|
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435 void *trace_argument)
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436 {
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437 UNWIND_HISTORY_TABLE ms_history;
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438 CONTEXT ms_context;
|
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439 struct _Unwind_Context gcc_context;
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440 DISPATCHER_CONTEXT disp_context;
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441
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442 memset (&ms_history, 0, sizeof(ms_history));
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443 memset (&gcc_context, 0, sizeof(gcc_context));
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444 memset (&disp_context, 0, sizeof(disp_context));
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445
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446 ms_context.ContextFlags = CONTEXT_ALL;
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447 RtlCaptureContext (&ms_context);
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448
|
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449 gcc_context.disp = &disp_context;
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|
450 gcc_context.disp->ContextRecord = &ms_context;
|
|
451 gcc_context.disp->HistoryTable = &ms_history;
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452
|
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453 while (1)
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454 {
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455 gcc_context.disp->ControlPc = ms_context.Rip;
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|
456 gcc_context.disp->FunctionEntry
|
|
457 = RtlLookupFunctionEntry (ms_context.Rip, &gcc_context.disp->ImageBase,
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458 &ms_history);
|
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459
|
|
460 if (!gcc_context.disp->FunctionEntry)
|
|
461 return _URC_END_OF_STACK;
|
|
462
|
|
463 gcc_context.disp->LanguageHandler
|
|
464 = RtlVirtualUnwind (0, gcc_context.disp->ImageBase, ms_context.Rip,
|
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465 gcc_context.disp->FunctionEntry, &ms_context,
|
|
466 &gcc_context.disp->HandlerData,
|
|
467 &gcc_context.disp->EstablisherFrame, NULL);
|
|
468
|
|
469 /* Call trace function. */
|
|
470 if (trace (&gcc_context, trace_argument) != _URC_NO_REASON)
|
|
471 return _URC_FATAL_PHASE1_ERROR;
|
|
472
|
|
473 /* ??? Check for invalid stack pointer. */
|
|
474 if (ms_context.Rip == 0)
|
|
475 return _URC_END_OF_STACK;
|
|
476 }
|
|
477 }
|
|
478 #endif /* __SEH__ && !defined (__USING_SJLJ_EXCEPTIONS__) */
|